Version NX6
Restart does not help :(
In attachment there are two files.
Assembly (kamera#2.prt)
File with ladder (lestnica.prt)
maybe on other machine it will work....
http://files.engineering.com/getfile.aspx?folder=f271ba75-024e-40aa-bab7-cc9696e77951&file=my.zip
I'm create two asseblies with refference to component "ladder.prt".
In ladder.prt I have created ladder with variable number of steps (Instance array)
In first assemly I assign interpart reference in Expressions
"ladder"::p75 = 10
in second assembly
"ladder"::p75 = 6
then I save both...